1. Field of Invention
This invention relates to sampling electronic signals. More particularly, this invention is directed to sampling electronic positioning signals generated by induced current linear and rotary position transducers.
2. Description of Related Art
Various movement or position transducing systems are currently available. U.S. patent application Ser. No. 08/788,469, filed Jan. 29, 1997, and incorporated herein by reference in its entirety, discloses an absolute position transducer for high accuracy applications, such as linear or rotary encoders, electronic calipers and the like. The absolute position transducer uses two members movable relative to each other. The first member contains at least one active transmitter for generating a magnetic field and at least one receiver for receiving the generated magnetic field. The passive second member includes passive flux modulating elements that modulate the received field depending on their position relative to the at least one receiver. An electronic circuit coupled to the at least one transmitter and the at least one receiver compares the outputs of the at least one receiver, evaluates the absolute position between the two members, and exhibits the position on a display. The inductive absolute position transducer determines the absolute position between the two members.
Furthermore, U.S. patent application Ser. No. 08/834,432, filed Apr. 16, 1997 and incorporated herein by reference in its entirety, discloses an induced current position transducer with winding configurations that increase the proportion of the useful output signal component relative to the extraneous ("offset") components of the output signal. This is accomplished by winding configurations that minimize and nullify the extraneous coupling between the transmitter and receiver windings.
However, the precision measurement systems using the above transducers must generate and capture two or more positioning signals to absolutely determine any given position. Since the two members, for which the position signals are generated, continue to change position before and after the measurement time, the two or more positioning signals must be sampled at exactly the same time in order to obtain the most precise position, i.e., without incurring a positional error that increases as the velocity of motion increases.
However, a single signal capture circuit cannot record and process two or more processing signals at the exact same time in order to generate the extremely precise position measurements. Therefore, to have two or more position signals sampled at the same time, a precision measurement system would require a separate signal capture circuit to capture each positioning signal. Moreover, using two or more signal capture circuits is impractical for small precision measuring devices due to space, power, and cost requirements.